Keeping up with the news of synthetic biology means I often see a lot of kooky things. There's the delightfully kooky iGEM project ideas or news of cyborg yeast (more on that hopefully sometime soon), a few conspiracy theory websites, and lots of newspaper articles with headlines like (I'm paraphrasing here) "Synthetic Biology Will Soon Kill Us All" or "Every Problem in the Entire World to be Solved by Synthetic Biology in the Next Decade." This oscillation between certain death and techno-utopia is what Drew Endy calls "The Half-pipe of Doom," the inescapable binary of equally implausible hype surrounding the field. I've gotten used to these headlines, enough that I groan and roll my eyes a little less each time I see them pop up, but yesterday I saw a headline that shocked me out of my hype-induced complacency. A short article in the Forbes magazine Techonomy conference coverage claimed: "For Synthetic Biologists, the Lab is the Place to Procreate."

This is not an article about scientists finding their mates amongst labmates, but an article about how synthetic biologists will in the next few decades be able synthesize and edit human genomes, becoming designers of human children. What's perhaps most shocking is that the article isn't by or about alarmist conspiracy theorists, but rather summarizes a short talk by Andrew Hessel at the conference. Hessel is a techno-evangelist, a speaker at tech conferences far and wide and the co-chair of Biotechnology at Singularity University. He speaks as a promoter of synthetic biology technology, but he certainly doesn't speak on behalf of all synthetic biologists, and most definitely not when he's talking about synthetic babies.

Hessel starts with an interesting story. As a young man he decided he didn't want to have children and asked his doctor for a vasectomy. There are many reasons why someone would not to want to have kids, and his story of not knowing how to "optimize childhood" for his offspring is kind of cute until you realize that he actually thinks of children as potential engineering projects to be optimized. After six years of trying to convince his doctors that a young person can decide that they don't want to have children, he gets his vasectomy and is left with a deep interest in medical science and genomics. But his point isn't really about medical paternalism and doctors not listening to their patients, but about how his ideas towards parenting changed with the advent of genome synthesis technology. After years learning to read and comprehend DNA sequence and the falling cost of writing DNA sequence from genes to whole genomes he says "the 180 degree shift in my thinking has been: it's time to procreate, to be a pro-creator of life and to be the best parent I can be."

Would an engineered baby be able to have an "optimized childhood"? What is an "optimal" child? Who gets to decide what kind of "edits" will be made to the genome? What happens to the "failed" experiments? What kind of life does an experiment have in the first place? Hessel says that synthetic biology will make cloning seem "organic," but the debates over human cloning have left us with some clear ethical boundaries about what experiments on humans are acceptable, boundaries that still hold in light of new technologies.

Of the many kooky futurist scenarios about biotechnology I've read, one that I really enjoyed and keep coming back to is the first chapter of Bruce Sterling's Tomorrow Now: Envisioning the Next 50 Years. In this chapter Sterling gets into all the messy biological, technological, and social complexity of biotechnology and in so doing avoids swinging back and forth in the simplistic Half-pipe of Doom. To Sterling, the answer to why we shouldn't engineer human genomes is to imagine actually being the first clone or the first engineered superbaby:

Forget about the cloned baby. Instead, let's talk about you. You are the cloned baby...Your "parents," or rather, your technical sponsors, carried out their weird goal, and you were their end product. You are the child they have on their hands--not the child of their love, of course, but the child of their boundary-shattering technological ambition, carried out in the teeth of stiff social resentment...Unlike, say a complaisant and brainless E. coli cell, you are fully capable of holding lasting grudges...Who asked your permission to transform you into a cutting-edge freak, a crass industrial experiment?...[You are] the guinea pig superbaby...You are a beta-release superhuman. You are merely a prototype. And since the people who built you are incapable of thinking through the issues, you are almost certainly a hack job.

No human design can take into account all the possible ways that it can interact with the world, whether the object being designed is a car, a computer, or a genome. No design of a human can control everything about how that person will feel or how that person will live or who that person will be. Even at the molecular scale, humans are much more than the sequence of letters of their DNA; genes interact with the cell and the environment in ways that shape how the genes are expressed and how they are passed to our offspring, our bodies are made up not only of human cells with human genomes but also trillions of bacterial cells that live in our gut, on our skin, and even inside our cells as mitochondria. At the human scale, people are shaped not just by their genes but also by their circumstances, their education, their diet, the places, events, and happenings of their lives, their friends and family, their society, their culture. Identical twins have the same genome but are never the same people. No design is complete, no system is perfectly determined, and even if there were an "optimal" person no matter how good computer-aided design of genomes gets we won't ever be able to design them.

We can aspire to the good side of the Half-pipe of Doom, but we have to design for the real world, the messy, complex, imperfect, social world. As Sterling writes, "We can describe a geneticized world that seems safe, efficient, and logical--a world that fulfills the promise that genetics offers. But trend is not destiny. Even the best technical prognosis is merely a child-rearing guidebook. No kid in the real world ever gets raised by a book." There is no guide to an optimized childhood, and there is no way to optimize a human life.